RU2676540C1 - Steady rest for additional support of central workpiece regions during machining, in particular bearing points on crankshafts, and grinding machine having such steady rest - Google Patents

Abstract

FIELD: manufacturing technology.SUBSTANCE: invention relates to a steady rest for additional support of the central regions of workpieces during machining of central workpiece regions using a grinding machine. Said steady rest for grinding is adapted to be brought from the retracted position to the position of additional support to the region of the workpiece and has at least two supporting parts that can be advanced onto the region of the workpiece. Said supporting parts are each located on one side edge forming a fork with two arms, an opening prism on the arm of the rest in a fixed position relative to each other and the arm of the rest and in the support position below the center relative to the longitudinal axis of the region of the workpiece. Further, the bisection formed between the two supporting parts has a constant acute angle with a perpendicular passing through the longitudinal axis of the region of the workpiece. Said steady rest can be advanced to the workpiece region to be machined along the given bisection with the ability of control at the CNC.EFFECT: roundness error rates in the central regions of workpieces to be machined decreases.16 cl, 8 dwg

Description

FIELD OF THE INVENTION

The invention relates to a rest for additional support of the central zones of the processed products during processing of the central and / or off-center zones of the processed products, in particular parts of the shafts, in particular crankshafts, which are applied to the supporting sections during grinding. The invention also relates to a grinding machine with such a backrest.

State of the art

Lunettes for additional support of the central zones of the processed products during processing of the central and / or off-center zones of the processed products, in particular, supporting sections, in particular crankshafts, are known. These lunettes are designed to create additional support during grinding for the so-called relatively flexible workpieces, for example, crankshafts, so that, as a result of the application of grinding forces, if possible, or at least only slight deformation of the workpiece being ground.

Grinding machines for grinding crankshafts, in a known manner, typically use AROBOTECH lunettes, which are preferably used up to shaft diameters or main bearing diameters on crankshafts, for example 70-80 mm. For large parts of shafts or crankshafts for which lunettes must be used during grinding, the use of known lunettes has the disadvantage that they often require a large constructive space. Owing to their constructive implementation, these well-known lunettes with their cams, when loading or unloading the processed products, must be retracted. These well-known lunettes usually have three cams, which are often coated with polycrystalline diamond or cubic boron nitride. Due to an embodiment with three cams, the corresponding support portion provided with an additional support is “clamped”, the support sections provided with an additional support being provided with additional support between the support elements coated with polycrystalline diamond in a diameter range of more than 180 °, for example, about 210 °. The workpiece is thereby "clamped" in its position in a self-centering manner, and the cams are fed in the direction of the center of the workpiece, that is, in the center relative to the diameter of the support. The movements of the individual cams of the lunette are mechanically forcibly connected, which leads to the formation of a relatively complex mechanical system. A “clamp” at three fixed points requires a good, at least pre-machined, support section for installing the rest. Summing up the backrest is therefore, due to the previously mentioned reasons, difficult. The mechanical forced connection of the three cams of a known lunette requires relatively large forces transmitted during feeding, which leads to an increase in the rut on the supporting sections provided with an additional support. In particular, it is known about the possibility of using so-called two-point lunettes for processed products of a larger diameter, moreover, two, independently capable of supplying processed products, lining, optionally provided with a coating of polycrystalline diamond, respectively, are served by means of separate, adjusted computer numerical control system, axes. The use of two separate axes adjusted by the computer numerical control system increases the production costs of such lunettes and, therefore, their cost, as a result of which such lunettes are technically very expensive and extremely expensive. Both reference points or reference zones of such a well-known two-point lunette are usually located at right angles to each other, with one reference point or reference zone being supplied to the reference section from below, and the other reference point or reference zone is fed to the reference section opposite to the grinding circle.

However, lunettes are already known in which two supporting sections are arranged with forced regulation, as in US Pat. No. 6,257,972 B1, and are supported in the direction of the third, opposite supporting section. The individual supporting elements of the lunette are either installed by means of abutments or are adjacent to the support subjected to finishing by grinding. The supply of the rest in the process of grinding the place of the rest is not provided, as well as impossible.

From patent DE 102011015205 B3 there is further known a two-point lunette with two supporting parts fixedly located relative to each other. This known lunette for creating horizontal and vertical additional support of the workpiece has two support elements arranged with lateral clearance relative to each other, the support elements are arranged, and the support elements are located on the mounting slide movably carried along the base and the installation gate is movable in the radial direction relative to the workpiece, so that both support elements are made with the possibility of joint supply to about workable product. The radial adjustment of the installation gate is carried out against the force of the spring, so that there is an additional movable element between the workpiece provided with an additional support and the support base of the lunette itself. The radial runout accuracy value obtained at best lies, therefore, within a few microns.

Disclosure of invention

The proposed invention is based on the task of creating a steady rest and a grinding machine with such a rest, by means of which it is possible to improve the roundness error in the central zones of the workpiece to values less than 1 μm.

Such high-precision results of grinding by radial runout are achieved by means of a rest with the features of paragraph 1 of the claims and, accordingly, by means of a grinding machine with the characteristics of paragraph 13 of the claims. Reasonable improvement options are defined in the respective dependent claims.

Further, when using the term “central support section”, such central zones of the workpiece that are implemented exactly in the center, but are not necessarily support areas on the workpiece or on the shaft part, should be understood and implied. Equally, the term “shaft part” should also mean a workpiece that has a central zone.

Designed to create additional support for the central supporting sections during processing of the central and / or offset from the center of the supporting sections of the shaft parts of the lunette in accordance with the invention, which, under the conditions of use, moves from the retracted position in order to create additional support during grinding to the position of the additional support to the supporting a portion of the shaft part, which is, in particular, a crankshaft, is designed in such a way that at least two testify to the support portion of the support. These supporting parts are the elements that actually create additional support and create additional support for the grinding section to be ground in the respective peripheral zones located at a distance from each other, and the distance between the peripheral zones is determined by the distance between the two supporting parts. The lunette in its front zone is made in the form of a prism, which creates a fork-shaped additional support for the shaft part with its supporting parts in the position of creating an additional support. The prism has two forming a fork of the shoulder of the console console, on which, respectively, is the supporting part, and the supporting part, with the formation of the angle of the solution between them, are each located on one side edge of the shoulder of the prism. The position of the supporting parts relative to each other and the console of the lunette is constant. This means that the mounting locations of the supporting parts relative to each other are located in a fixed manner. In addition, the lunette with its prism opening upward in the position of creating an additional support is located below the center relative to the longitudinal axis of the supporting section, and the bisector formed between the two supporting parts due to the position on the shoulders of the console of the lunette has a constant acute angle with a perpendicular passing through the longitudinal axis of the supporting section . The lunette has the so-called axis, which is adjusted by the computer numerical control system, which allows the lunette to be adjusted to feed along the bisector to the support section until the lunette is in the position of creating an additional support and grasps, and also creates an additional support for the machined by grinding the shaft parts.

Fixed relative to each other, the location of the supporting parts on the lateral edges of the lunar prism in combination with the grip of the shaft part intended for grinding by grinding below the center in order to create additional support with bisectors formed between the supporting parts through the longitudinal axis of the supporting section ensures that the supporting zone of the lunette is located below the formed by means of the axis of rotation of the grinding wheel and the central longitudinal axis of the workpiece, the plane, i.e. below the center, is machined of the product, that is, below the center. When grinding, this is an advantage insofar as the supporting section supplied with the additional support is never completely round, and due to the position of the additional support in accordance with the invention and the embodiment of the rest, the usually existing roundness errors when grinding the supporting section are not reproduced or are copied on the grinding being subjected reference area in a continuous manner. If, as in the prior art, the support points of two supporting parts are located symmetrically absolutely exactly opposite to the grinding area, then the bumps are reproduced again during grinding of the supporting section, which means that during grinding the bumps are not only continuously reproduced in shape and size, but also, under certain circumstances, they also increase.

By means of the lunette in accordance with the invention, a more gentle additional support is realized for the corresponding reference section, since due to the presence of a separate, computer-controlled numerical control system, the axis can be purposefully installed on the reference section, and moreover, in such a way that the bisector passes between the two reference parts continuously through the central longitudinal axis or the axis of rotation of the support section. And this also leads to a decrease in rut due to the rest on the reference place.

In general, the prismatic support for the lunette in accordance with the invention has a selected prism angle, that is, the lateral edges of the prism lunette console relative to each other, whereby the supporting portion provided with the additional support is gripped as if by the type of fork and is additionally supported. Depending on the shape and size of the shaft part provided with an additional support and on the technical requirements, the corresponding used rest may have a different angle of the supporting prism. In principle, in a preferred embodiment, it is also possible that the shoulders of the prism console of the lunette console are adjustable with respect to each other, so that the lunette can better meet different requirements with respect to the diameter of the grinding parts to be provided and the shaft parts provided with additional support.

In this case, however, it is necessary that the lateral edges of the prism in their respective angular arrangement agreed upon with a specific task for creating an additional support be positioned and fixed relative to each other so rigidly that the support parts for performing the additional support creation task have a fixed location relative to each other and, if possible, could carry out fluctuations, however, not to increase processing errors. By selecting in accordance with the invention the ratios of the angle and location of the supporting parts on the lateral edges of the respective arms of the arm prism arm, the lunettes in the preferred embodiment of roundness on the workpiece can be substantially improved during grinding, so that roundness errors of less than 1 μm or even much lower can be achieved. The use of a lunette in accordance with the invention contributes, however, not only to the improvement of roundness in a general sense, but also by means of a lunette in accordance with the invention, a reduction in waviness is achieved with waviness of a lower order, as a result of which higher quality products can be made, and moreover, without the need for use after grinding other work or operations. The ability to manufacture high-precision products without additional manufacturing costs leads to a significant reduction in cost. The lunette in accordance with the invention is therefore a technically good and inexpensive solution, which, in particular, can be used for parts of shafts with a large diameter, in the preferred embodiment, more than 70 mm, and in the preferred embodiment also for crankshafts, the diameter of the main bearing, if necessary, can also be less than 70 mm. For processed products of small, up to medium, dimensions, the rest in accordance with the invention, of course, can also be used.

Additional roundness adjustments by superimposing X-axis adjustments that are based on the measured values are calculated and performed by the control of the grinding machine, usually already used for off-center bearing sections, such as a connecting rod bearing. It is understood that such roundness adjustments can also be used for the main bearing. To further improve circularity in the central supporting sections, such a correction of circularity can be used in addition to the use of the lunette in accordance with the invention.

In a preferred embodiment, the lunette to create an additional support is installed on the supporting section, subjected to fine grinding, however, it is also possible that the lunette is installed on the supporting section, sanded in a straight line, and in the latter case, not only an additional support is created, due to the dead weight of the processed product , but also, at least to a certain extent, the grinding force generated by the grinding wheel is perceived by the rest.

In accordance with an embodiment of the invention, the lunette console on which the prism is located, by means of only one servomotor operating on a threaded spindle, is movable between a retracted position and an additional support position. By this, it is achieved that the supporting parts, which are located at a constant angular distance inside the prism, are reliably and reproducibly applied to the supporting section provided with the additional support in order to create an additional support for the supporting section.

In a preferred embodiment, the bisector forms such an angle with the perpendicular that arising during grinding, resulting from the work of the grinding wheel, the forces press the supporting sections into the prism to the supporting parts, with the fixing of the supporting sections. The angle between the bisector and the perpendicular is selected in such a way that the supporting parts abut relative to the central longitudinal axis of the workpiece below the center, so that when grinding, grinding forces push the workpiece into the prism and the supporting parts, so to speak. Through this, the workpiece is held in a prism and locked in position by means of the supporting parts.

Further, in a preferred embodiment, the lunette with its adjusted computer numerical control system for the feed axis is implemented in such a way that it can be brought so far to the work piece provided with the additional support or the workpiece provided with the additional support that the support position corresponds to the final feed position, so that the luff is adjacent to the abraded support section or to the abraded part of the shaft. However, it is also possible that the position of the rest to create additional support is the feed position with the grinding allowance still available. This means that the rest during grinding, despite the fact that the final size on the abutment being subjected to grinding has not yet been achieved, nevertheless, creating a support acts on this polished in a straight abutment, and during grinding, while creating an additional support for the reference section of the prism, that is, the console of the lunette with the prism, by means of the supporting parts is brought to the final size. It is particularly preferred if the prism feed adjusted by the computer numerical control system is synchronized with the feed of the grinding wheel. Due to such an embodiment, when the axle feed axis and the grinding wheel feed axis are respectively adjusted by a computer numerical control system, both axes are essentially freely programmable.

When a lunette is installed on a finished grinding base, the lunette can be set to a predefined position precisely on the workpiece by means of a computer-controlled numerical control axis of the control axis. The final position in this case corresponds to the final size of the workpiece to be ground. In particular, when the lunette, that is, the lunette console with the prism, is moved to the desired end position by means of hydraulic actuators, it is possible to provide reliable additional support for the pre-finished grinding sections using the supporting lance prism. Such a lunette is relatively simple in design and, therefore, also inexpensive to manufacture.

In a preferred embodiment, however, it is also possible to use a backrest to create additional support on the abutment, which is ground in a straight line, and which, therefore, still has a certain allowance for grinding. For this, it is necessary that the rest be supplied exactly in accordance with the grinding allowance still available during grinding, that is, in accordance with the difference between the actual grinding allowance and the final size. This means that the lunette at any moment of time must be precisely brought to the grinding allowance radially polished per unit time in the reference section. This requires synchronization between the adjusted system of computer numerical program control of the axis of the lunette and the adjusted system of computer numerical program control of the X-axis of the grinding wheel. In a preferred embodiment, this can be solved especially simply due to the fact that the supporting prism on the workpiece by means of a system-adjusted computer numerical program control of movement is supplied linearly. Due to such a linear feed, it is possible to achieve synchronous feed values to the depth of the X-axis of the feed of the grinding wheel, on the one hand, and the feed axis of the supporting prism, on the other hand, and the supply of the lance prism follows the feed of the grinding wheel, that is, both feed axes are electronic way connected to each other.

For reasons of accuracy and rational considerations from the point of view of grinding technology, it may be preferable to refuse accurate synchronization between the X-axis of the grinding wheel feed and the adjusted computer numerical control system for the axis of the lunette. The supporting prism can, for example, periodically during grinding of the support section also be purposefully set so that the part of the shaft to be subjected to grinding in the given zone is subjected to excessive pressure. Under the "overpressure" in the framework of this invention it should be understood that part of the shaft during grinding in the area from a few microns to several hundredths of a mm is subjected to overpressure above average values. In a preferred embodiment, this can also be implemented in such a way that the support prism is periodically adjusted during grinding of the support section to a certain small value, either lower or higher, with overpressure. In a preferred embodiment, the degree of excess pressure is equal to the achieved accuracy of the structural element being processed, as well as the grinding forces introduced by the grinding wheel into the workpiece. Other important factors of influence are also the geometry and rigidity of the workpiece.

In a preferred embodiment, the respective feed movements of the grinding wheel and the rest through their respective axes adjusted by the computer numerical programmed control system are carried out in such a way that at each time point in the grinding process of the supporting section it is precisely held at an average value. However, in a preferred embodiment, it is also possible to carry out grinding slightly below the center or above the center. In particular, a preferred embodiment of the inertia feed of the steady rest is provided for grinding the central bearing sections, for example, the main bearings of the crankshaft.

The lunette in accordance with the invention can also be used for grinding cam shafts or other parts of shafts. As is known, the grinding cams are located next to the supporting sections. The same applies to the main bearings on the crankshafts, if, for example, they undergo grinding by the pendulum stroke. In this case, the cam or connecting rod bearings are polished in such a way that during the grinding revolution of the workpiece, unequal power relations through grinding affect the workpiece. In a preferred embodiment, for such an application, a lunette is used, in which an additional pivot arm located on the prism is provided, which has an additional support part in its opposite pivot axis of the end zone. If, in accordance with the invention, in the lunette, the support parts below the center act on the support portion provided with the additional support, then the pivot arm is calculated so that the additional part is pivoted from above into its abutment position to the abutment portion and by setting the rotary arm in its abutment position additional support of the supporting section from above is carried out. In this case, in the preferred embodiment, three bearing parts are provided in the form of a three-point bearing for the grinding section to be ground. Thus, it is achieved that the supporting section at any time during processing is firmly adjacent to the supporting prism, even when, for example, unstable, due to grinding by the pendulum stroke or due to cam grinding, force ratios also affect the lunette during the grinding process.

In a preferred embodiment, the rotation of the pivot arm is carried out hydraulically, pneumatically or electronically. This ensures that the supporting section provided with the additional support always adheres exactly to the supporting prism with a predetermined adjustable force. When carrying out hydraulic or pneumatic adjustment of the pivoting movement, at least one pressure sensor is provided for adjusting the pressure force.

In a further preferred embodiment, the hydraulically or pneumatically adjusted pivot arm pivots to a limited pivot value, for example by means of a stop. In this case, then the support portion is pressed against the support portion by means of the spring force generated by the spring. In an embodiment of electric control of the pivoting movement, the pivoting lever is pivoted to a predetermined pivoting position, and the pressing force to the supporting portion is created due to the fact that the supporting portion is pressed against the supporting portion by means of the spring generated pressing force.

By calculating the parameters of the spring, it is thus possible to adjust or select a preliminary clamping force, depending on the corresponding seating position of the pivot arm and, thus, the supporting part on the ground in a straight line, subjected to fine grinding, or on the supporting section intended for grinding.

Similarly to the generation of pressing force by means of a spring element, a hydraulically and pneumatically controlled element can also be used. The calculation of the pressing force can then be determined and adjusted by means of a pressure sensor.

The adjoining position of the additional supporting part is in this case opposed to the positions of the supporting parts of the prism.

The position of the fit can be located on the bisectors of the supporting parts of the supporting prism, however, this is not an essential condition for technical functioning.

Often the position of the additional supporting prism is not even located on the bisectors of the supporting parts of the supporting prism, since displacement from this position due to unequal angular distribution prevents the formation of non-circularities during the grinding process of the supporting section.

In accordance with an embodiment of the invention, the support parts preferably have smooth surfaces, so that when in contact with the support portion provided with the additional support, in any case, purely theoretically, a linear contact is created. Further, in a preferred embodiment, the surface of the supporting parts can be implemented in the form of a convex curved plane. The surface of the support parts thus realized provides even better targeted contact between the support parts and the surface of the corresponding support portion provided with additional support, and even if the support parts deviate from the cylindrical shape. Further, in a preferred embodiment, the supporting parts are provided with a central groove that divides the surface of the supporting parts into two supporting sections. Due to this, on the one hand, a good supporting action can be obtained, since an additional support is created across the entire width of the supporting part. In a preferred embodiment, the surfaces provided with the additional support are slightly spherical and their lateral edges are rounded so that the surface provided with the additional support cannot be damaged by them.

For reasons of wear resistance, the support parts are preferably provided with surfaces coated with cubic boron nitride or polycrystalline diamond. Due to this, a long service life of the supporting parts can be realized, which already with the possibility of replacement are located on the fork-shaped consoles of the prism.

The next preferred embodiment of the lunette is achieved due to the fact that the supporting parts on the lateral edges of the prism are arranged to swing around an axis passing under 90 °, that is, perpendicular to the longitudinal axis (in the plane direction between the axis of rotation of the grinding wheel and the axis of rotation of the workpiece) grinding part of the shaft. This degree of freedom of the supporting parts, which is available due to the possibility of swinging, provides a uniform and improved fit to the surface of the shaft part provided with the additional support, even when the shaft part must be ground slightly spherically or concave. A further advantage of this additional axis of swing of the support parts is that in the case of non-absolutely cylindrical support sections, whether due to grinding errors or the desired shape of the support, the circumstance that the edges of the support parts during the creation of the additional support can be included in the corresponding the surface provided with additional support and, as a result, could leave behind undesirable traces of grinding. Without the support part of the system of support parts installed in a swinging manner at 90 ° to the longitudinal axis of the support part, precisely when the form of the support part deviates from the cylindrical one, no linear contact would form to create additional support, but there would be point contact. This point contact would, however, cause an increased contact compression stress on the surface, which could also lead to damage to the supporting surface provided with an additional support. On the contrary, by uniformly adhering the support parts to the surface of the support part polished in a straight line and provided with additional support, in general, due to less pressure on the surface, increased accuracy is achieved, so that by such an action it is possible to increase accuracy with respect to roundness in the presence of a roundness error even with values clearly less than 1 micron.

In accordance with a further aspect of the invention, there is provided a grinding machine which is designed to grind central and / or off-center zones of workpieces, or supporting sections on workpieces, or parts of shafts, in particular crankshafts. The grinding machine has a steady rest with the features described above in accordance with the invention. Additionally, the grinding machine has a control device by which, during grinding or after grinding of the supporting section, the grinding wheel can be installed in the central zone of the workpiece while the grinding wheel, in accordance with the application, can be supplied until the final size of the supporting section is reached. By means of such a grinding machine that uses a lunette in accordance with the invention, roundness deviations of even clearly less than 1 μm can be obtained even if, for example, grinding of the main bearings of the crankshafts or cams of the cam shafts is carried out during grinding by the swingarm, and, thanks to this, you can abandon the variable application of forces to subjected to grinding of the structural element.

In a preferred embodiment, the grinding machine in accordance with the invention has a measuring device that transmits to the control device signals for measuring the diameter of the zone of the workpiece for the feed position of the rest in the zone of the workpiece. Based on this, the feed positions of the lunette and the grinding wheel are adjusted. When the rest is in contact with the central zone of the workpiece, which is ground in a straight line and still has an allowance with respect to the final size, the rest can be filed in the preferred embodiment in accordance with the grinding wheel that has not yet been removed, corresponding to the actual allowance for grinding the grinding wheel.

It is understood that the control device and the measuring device can be provided in the form of a structural unit, and can also exist in the form of separate devices, that is, a separate control device and a separate measuring device can be provided, and the measuring device generates signals based on the measured values measurements that are supplied to the control device, so that the control device, in the end, implements synchronous or slightly asynchronous control under whose backrest and the corresponding grinding wheel supplied with an additional support, a support portion for the case where the steady rest in accordance with the constantly decreasing due grinding passes, the grinding allowance is brought to finished size is subjected to grinding portion. A case of deviation from the feed synchronism can, for example, occur when the structural element to be grinded must be subjected to a slight overpressure by means of a rest, so that, for example, it can compensate for the grinding forces introduced into the structural element by means of a grinding wheel, so that also grinding result improved.

In accordance with an improvement option, the control device is implemented in such a way that, when using the measured value based on the established roundness errors, an additional roundness correction for the X-axis of the grinding wheel adjusted by the system of computer numerical control for overlapping can be superimposed on the feed rate of the grinding wheel.

Brief Description of the Drawings

Other embodiments and details of the invention are described based on embodiments through the following drawings, in which:

FIG. 1 is a basic construction of a grinding machine with a backrest in accordance with the invention;

FIG. 2 is an enlarged detailed view of a straightened crankshaft with a rest in accordance with the invention in the retracted position and in the position of creating an additional support;

FIG. 3 is a principal front view of a lunette in accordance with the invention in the direction of arrow V in accordance with FIG. 2;

FIG. 4 is a sectional view of a lunette console for depicting a guide for linearly moving a support prism along a section plane W-W;

FIG. 5 a lunette in accordance with the invention in a section along the section line U-U in accordance with FIG. four;

FIG. 6A is a cross-sectional view of a support part in a support prism of a lunette with the possibility of rotation of the support part around a rotary axis of the shaft portion provided with additional support of the shaft passing at 90 ° to the longitudinal axis;

FIG. 6B is a plan view of a support portion located on a prism of a lunette;

FIG. 6C is a perspective view of a support portion with a central groove and pivotability in accordance with FIG. 6A and, accordingly, 6B;

FIG. 7 is a perspective view of a lunette in accordance with the invention with supporting parts in accordance with FIG. 6a and, accordingly, 6B; and

FIG. 8 is a detailed side view in accordance with FIG. 2, however, for another exemplary embodiment with an additional pivoting lever on the rest in accordance with the image on which the third supporting part is mounted.

The implementation of the invention

In FIG. 1 is a side view of a basic construction of a grinding machine equipped with a lunette in accordance with the invention. A cross support is installed on the machine bed 1 for adjusting the movement of the grinding wheel 4 located on the grinding headstock 3 by the computer-controlled numerical program control system, for feeding it to the grinding being machined having a longitudinal axis 5, the workpiece 6. The headstock 3 is made in the known manner in the form of a cross support so that it is possible to feed the grinding head 3 with the grinding wheel 4 parallel to the longitudinal central axis of the workpiece, that is, its rotation axis Niya, and perpendicular to the central longitudinal axis of the workpiece. The workpiece 6 is held on the headstock not shown, and the grinding wheel 4 is arranged to move relative to the central longitudinal axis of the workpiece 6 along the Z axis adjusted by the computer numerical program control system. The headstock not shown is installed in the front area of the grinding machine, on the machine bed on a grinding table, on which there is also a rotary drive mechanism for the workpiece, a tailstock and a rest 7 to create additional body support for the workpiece on the supporting section. In a preferred embodiment, an additional support is created for that supporting section, which is ground straight. However, an additional support is also possible for that supporting portion which has already been ground. The drive mechanism not shown for the workpiece is symbolically indicated by a double arrow 8 and is also controlled by a computer numerical control system and denoted as the C-axis.

In FIG. 2 is a detailed view of a grinding machine according to FIG. 1, on which the grinding wheel 4 carries out grinding just in engagement with the workpiece 6 in the form of the main bearing of the crankshaft. The central longitudinal axis of the axle of the main bearing runs parallel to the axis of rotation of the grinding wheel 4. On the grinding table 25 is installed a rest 7. The rest 7 has a recess formed on the console of the rest, which is made in the form of a prism and has support parts 11 on its side edges 11. The rest 7 is located on the grinding table 25 in such a way that the support lines 20 (with the right support part 7 shown in the figure) formed by means of the support parts in contact with the support portion 9 are located approximately 7 ° below the center brabatyvaemogo products. This means that the support prism is generally located relative to the longitudinal axis of the workpiece and the axis of rotation of the grinding wheel, which are located in one plane, below the center.

In FIG. 2, the position of the lunette creating additional support is indicated by dashed lines, while the retracted position, in which, for example, extraction or re-securing of the workpiece can be carried out, is shown by solid lines. An angle a of about 7 ° proved to be particularly preferable in the grinding process, since the supporting portion 9 provided with an additional support is never 100% absolutely round. Due to this arrangement, located below the center, of the direct additional support of the abutment section being subjected to grinding 9, roundness errors on the abutment site during grinding are again not reproduced on the abutment being subjected to grinding, which occurs in the prior art when the additional support for the abutment section is relative to the bisectors between the two supporting parts is located in the same plane of the axis of rotation of the grinding wheel and the longitudinal axis 5 of the workpiece.

In the exemplary embodiment of FIG. 2 it is shown that the bisector passes between the supporting parts 11 of the prism 10 of the lunette 7 through the longitudinal axis 5 of the workpiece, that is, it is located clearly outside the plane formed by the longitudinal axis of the workpiece and the axis of rotation of the grinding wheel. The angle between the bisectors of the supporting parts in this embodiment is approximately 67 °, and due to this, an additional support is created below the center on the supporting section due to the adjacent prism 10. This 67 ° angle between the bisectors depends on the respective grinding task and the corresponding grinding conditions, and can be optimized through simple activities. Unexpectedly, the fact that due to this arrangement of the prism, the supporting sections with roundness errors can be ground to a size clearly less than 1 μm revealed itself. Such minor roundness errors can be achieved, in particular, because the rest, on the one hand, has a high degree of rigidity, and, on the other hand, the advantage of moving along the feed axis also adjusted by the computer numerical program control system. Due to this, under certain conditions, the lunet console with a supporting prism and actually supported support parts can be supplied to a support section 9 provided with an additional support. Using the threaded spindle 13, the lance supply to the support section equipped with an additional support can be guaranteed exactly along the bisectors that the center of the supporting portion in the direction of the feed axis of the grinding wheel is held in a certain way. The movement of the supporting prism along the axis adjusted along the bisector of the computer numerical programmed control system is ensured by a servomotor 12, which, by means of the coupling 17 located in the housing 16, acts on the threaded spindle 13 provided for supplying the supporting prism 10 from the retracted position, preferably of the type spherical planetary spindle. The lunette is fixed on the grinding table 25 by means of a holder, which has a guide 14 in the form of a dovetail.

Depicted on the grinding wheel 4, the downward arrow indicates the direction of rotation of the grinding wheel. The upward-pointing arrow pointing to the workpiece displays the rotational movement of the workpiece. The double arrow depicted in the upper part of the figure shows the axis of movement of the lunette feed from the retracted position to the position of creating the additional support adjusted by the computer numerical control system. The direction of rotation of the grinding wheel and / or the workpiece may, however, be the opposite.

The supporting parts 11 are made in the form of plates coated with cubic boron nitride or polycrystalline diamond, which are in direct contact with the supporting section 9 of the workpiece 6 in the lunette position, which creates additional support. This means that the support portion 9 of the workpiece 6 slides along these support portions 11 in a theoretical linear contact in the form of support lines 20. Depending on the material or grinding conditions, support portions coated with cubic boron nitride or polycrystalline diamond are used. The advantage of these materials is that they have high wear resistance.

In FIG. 3 is a front view of a lunette in accordance with the invention, in the direction shown in FIG. 2 and indicated by the letter V arrows. The lower holder for connecting the lunette with the grinding table 25 has a guide 14 in the form of a dovetail. The guide by means of clamping screws 15 is fixed in a certain predetermined position. By means of such a stiff and providing a certain direction of adjustment, the latch 7 by means of its supporting prism 10 is adjusted so that it is adjusted in the center of the supporting portion 9 provided with an additional support, which means that the two supporting parts 11 provided with an additional support are simultaneously and uniformly adjacent to the workpiece 6 , and the axis of supply of the lunette from the retracted position passes into a position provided with additional support along the bisectors between the two supporting parts of the prism. This so-called alignment must be performed once and after adjustment is held in a fixed state.

The supporting parts 11 in the presented image are marked in front view. It can be seen that the supporting parts are fixed on the lateral edges of the prism by means of two screws and are implemented as through support plates. The swing axis 21 of the other supporting part on the prism 10 is also shown (see also the description of figures 6B-6C).

FIG. 4 is a partial sectional view in accordance with FIG. 2 along the section plane W-W. A guide is shown for linear movement of the support prism. The movement occurs along the guide rail 27, which is placed in the guide carriage 26. The drive is carried out by means of a threaded spindle 13. On the guide rail 27, ball or roller bearings are installed without a preload clearance. The position of the threaded spindle 13 near the guide rail 27 is shown.

In FIG. 5 is a partial sectional view of a lunette in accordance with the invention, which shows a guide rail 27 with a guide carriage 26. In addition, the drive is shown by a system-controlled computer numerical control of a servomotor 12 for mounting a support prism 10 on a supporting portion provided with an additional support. The drive for adjusting the supporting prism along the bisectors between the supporting parts 11 is made by means of a threaded spindle 13, which is at least partially placed in the housing 16. A coupling 17 is located in the housing 16, by means of which the servomotor 12 is connected to the threaded spindle 13. By means of the corresponding requirements programming controlled by the system of computer numerical control of the servomotor 12 is the feed movement of the supporting prism 10 in the control system w grinding machine with the greatest possible accuracy. The threaded spindle 13 is also held by a threaded nut 28.

The lunette is fixed on the grinding table 25 by means of a holder, from which the guide section 14 is shown in the cross-section as a dovetail. The lunette console 19 has a prism 10 at its front end, on the lateral edges of which the supporting parts 11 are located. It is also shown that the supporting parts 11 are arranged to swing about the rolling axis. The rolling axis of the respective supporting parts extends at 90 °, that is, perpendicular to the central longitudinal axis of the workpiece provided with the additional support in the direction from the side, that is, from the side of the grinding wheel, which in FIG. 5 is not shown. The presented partial sectional view corresponds to the section plane U-U in accordance with FIG. four.

FIG. 6A shows a partial cross-sectional view in enlarged view of the support portion 11 located on the lateral edge of the supporting prism of the support prism. It can be seen that the support portions 11 extend beyond the surface of the side edges 22, and moreover, toward the inside of the prism, so that the support portions are in contact with the additional support being provided, if necessary, grinded in a straight line, the workpiece by means of a reference line could provide the appropriate, creating additional support contact. The supporting part 11 with the possibility of a connector is mounted on a hinged bolt, which provides a swinging movement of the supporting part around the axis of rotation or the pivot axis 21. The advantage of such a swinging installation of the supporting parts is that, if necessary, they are not precisely and intentionally implemented not cylindrical, supplied additional support, the supporting sections always provide a stable and precisely defined fit of the supporting part to the supporting section provided with the additional support, that is, to its surface. Due to such a swinging arrangement of the support part, it is in any case prevented that when the support surface provided with the additional support deviates from the precisely cylindrical shape, the edge or edges of the support part are pressed into the surface of the workpiece supplied with additional support. The presented support part has two support zones, which are located on the sides of the support part made in the form of plates and are separated from each other by the so-called central groove 23. An advantage of this embodiment is that, by means of a central groove, two support zones are formed for each support part, which provide a reliable additional support, however, at the same time they form only one short linear contact, so that the result of the lunet fitting to the already sanded area of the support section is further reduced .

In FIG. 6B illustrates such an embodiment of the support portion in a plan view in accordance with FIG. 6A arrow. Depicted in FIG. 6B, a double arrow indicates the possibility of rotation of the support portion 11 about the axis 21 of the rolling.

And finally, in FIG. 6C is a perspective view of such a swinging support portion 11. By means of a central groove 23 on the support portion 11, one support portion is formed on both sides. The rotation, that is, the swing of the supporting part 11, is carried out along the axis 21 of the rolling. The following is an explanation of a portion of the side edge 22 of the prism.

Due to this embodiment, when the support parts have, respectively, two positioning support lines forming the support lines 20 and are additionally installed with the possibility of rocking, the support parts are adjacent to the workpiece 6 provided with additional support on its surface, that is, to the surface of the support section 9, absolutely evenly, even if the supporting section would have, for example, shape errors in terms of cylindricality or (intentionally) a certain taper. It is further preferred that the support portion 9 abuts in the prism even more stably without the so-called overload fit. In this embodiment, the support portion provided with the additional support abuts absolutely evenly against all four fit points or the short support lines 20. Due to this, an optimum support fit of the workpiece is achieved by means of the rest.

In FIG. 7 the lunette in accordance with the invention is presented in a perspective image in the form of a standard assembly. In particular, you can see the console 19 of the lunette, the prism 10, the support parts 11 mounted with the possibility of swinging, the guide carriage 26 with the guide rail 27, the servomotor 12 adjustable by the computer numerical control system, and also the holder for fixing to the grinding table with the guide 14 of the type dovetail. This lunette in accordance with the invention has a high degree of compactness and, due to this, in this embodiment, can provide exceptionally high-quality grinding results.

In FIG. 8 shows the following embodiment of a lunette in accordance with the invention. The view of FIG. 8 corresponds to a partial sectional view in accordance with FIG. 2, with the difference that, in accordance with this embodiment, an additional pivoting lever 18 with another supporting part 11 'is provided on the lunette. This embodiment of the lunette is especially necessary and makes sense when various grinding forces act on the workpiece to be ground during grinding. This is the case, for example, with pendulum grinding or when grinding non-cylindrical elements, for example, cams. Due to the fit of the pivot arm 18 by means of an additional third support part 11 ', a so-called three-point support reaction is formed. Due to this, a stable, accurate, realized by means of a steady rest, additional support for the workpiece being subjected to grinding is achieved.

In the embodiment proposed for consideration, the pivot arm 18 extends from above onto the surface of the supporting portion provided with additional support, either pneumatically or hydraulically, so that the workpiece is always precisely adjacent to the supporting prism with a predetermined force. In this case, the pressing force can be expediently adjusted or adjusted simply by the corresponding pressure of the pneumatic or hydraulic actuating elements for the pivoting arm 18. Moreover, the corresponding pressing pressure can be precisely coordinated with the grinding process, and moreover, during the grinding process it can be variably adjusted in accordance with it . Actuation of the pivoting arm 18 by means of an electric motor is equally possible, whereby the desired pressing force can be realized by means of a spring element or by means of a hydraulic or pneumatic element on the supporting part 11 '.

List of Reference Items

1 machine bed

2 cross support

3 grinding head

4 grinding wheel

5 central longitudinal axis of the zone of the workpiece

6 workpiece / shaft part

7 lunette

8 headstock of the processed product

9 zone of the processed product

10 prism / prismatic additional support

11, 11 'bearing parts

12 servomotor

13 threaded spindle

14 dovetail guide

15 clamping screws

16 building

17 clutch

18 rotary lever

19 lunette console

20 reference lines

21 swing axis

22 lateral edges of the prism

23 central groove

24 supporting section

25 grinding table

26 guide carriage

27 guide rail

28 threaded nut

Claims (16)

1. Lunette (7) for additional support of the central zones (9) of the processed products subjected to grinding on a grinding machine, in particular the supporting sections of the parts (6) of the shafts, in particular crankshafts, during the processing of the central and / or off-center zones of the processed products moreover, the grinding rest is made with the possibility of bringing from the retracted position to the position of the additional support to the area (9) of the workpiece and has at least two made with the possibility of feeding to the zone (9) of the workpiece parts (11) that create additional support for the zone (9) of the workpiece in the respective, located at a distance from each other, peripheral zones, and the workpiece (6) through its zone (9) is supported in the supporting position, characterized in that that the supporting parts (11) are made with the formation of the angle of the solution between them, each located on one lateral edge (22), forming a fork having two shoulders, in the form of an opening prism (10) on the console (19) of the lunette, located in a fixed position relative to each other and the console (19) of the lunette and in the supporting position below the center relative to the longitudinal axis (5) of the zone (9) of the workpiece, while the bisector formed between the two supporting parts (11) has a constant acute angle with passing through the longitudinal axis (5) zones (9) of the workpiece perpendicular and the rest can be supplied with the possibility of control to the section (9) of processing the workpiece for this bisector during CNC. 2. Lunette (7) according to claim 1, characterized in that the lunette console (19) is arranged to move between the retracted position and the supporting position by means of only one servo motor (12) working on the threaded spindle (13). 3. The lunette (7) according to claim 1 or 2, characterized in that a pivot arm (18) located on the console (19) of the lunette is provided, which has an additional supporting part (11 ') in its opposite rotary axis of the end zone, by which when the rotary lever (18) is rotated to its abutment position against the zone (9) of the workpiece, an additional support may be formed for it to press against the zone (9) of the workpiece. 4. Lunette (7) according to claim 3, characterized in that the rotation of the pivot arm (18) is carried out hydraulically, pneumatically or electrically. 5. Lunette (7) according to claim 3 or 4, characterized in that the pivot arm (18) in its abutment position exerts the pressing force of the additional supporting part (11 ') generated by the spring on the area (9) of the workpiece. 6. Lunette (7) according to one of claims 1 to 5, characterized in that the supporting parts (11, 11 ') have smooth, convexly curved or separated by means of a central groove (23) into at least two supporting sections (24) surface. 7. Lunette (7) according to one of claims 1 to 6, characterized in that the supporting parts (11, 11 ') have surfaces coated with cubic boron nitride or polycrystalline diamond. 8. Lunette (7) according to one of claims 1 to 7, characterized in that the supporting parts (11) are mounted on the lateral edges (22) of the prism (10) with the possibility of swinging around the zone (6) extending perpendicular to the longitudinal axis (5) workpiece axis (21). 9. A grinding machine for grinding central and / or off-center zones (9) of the workpiece (6), in particular supporting sections, in particular crankshafts, with a backrest (7) to create additional support for the central zones (9) of the workpiece, which, for grinding, is made with the possibility of bringing from the retracted position to the position of an additional support to the area of the workpiece and has at least two supporting parts (11) that are able to feed to the area (9) of the workpiece, which create an additional body support for the zone (9) of the workpiece in the respective peripheral zones located at a distance from each other, and the workpiece (6) is supported in its support position by means of its zone (9), and with a control device through which during grinding or after grinding the zone (9) of the workpiece with a grinding wheel (4), the lunette (7) can be installed in the central zone of the workpiece, and the grinding wheel (4) can be supplied until the final size of the supporting section is reached, about characterized in that the supporting parts (11) of the lunette (7), with the formation of the angle of the solution between them, are thus located in the grinder each on one side edge (22), forming a fork having two arms, an opening prism (10) on the console (19) the lunette in a rigid position relative to each other and the console (19) of the lunette and in the supporting position under the center relative to the longitudinal axis (5) of the zone (9) of the workpiece, that the bisector formed between the two supporting parts (11) has a constant acute angle with passing through the longitudinal axis (5) (9) of the workpiece perpendicular and the rest (7) can be supplied with the possibility of control to the workpiece processing section (9) for this bisector. 10. The grinding machine according to claim 9 with the rest, located on it in such a way that the bisector forms such an angle with the perpendicular that the resulting force with grinding in position fixes the zone (9) of the workpiece into the prism (10) against the supporting parts (eleven). 11. The grinding machine according to claim 9 or 10, in which the rest is carried out in such a way that the supporting position is the final feed position and the prism in the final position is adjacent to the supporting section processed by fine grinding (9). 12. The grinding machine according to one of claims 9 to 11, in which the rest is made in such a way that the supporting position is the feed position with the grinding allowance still available and during grinding, creating a support for the supporting section (9), prism (10) with supporting parts (11) can be fed to the final size. 13. The grinding machine according to claim 12, wherein the lunar prism (10) adjusted by the computer numerical program control system can be realized synchronously to the grinding wheel feed. 14. The grinding machine according to one of claims 9 to 13, which has a measuring device that transmits to the control device the signals for measuring the diameter of the zone (9) of the workpiece for the lance feed position and the position of the X-axes of the grinding wheel on the supporting section, based on which lance and grinding wheel feed positions. 15. The grinding machine according to one of claims 9 to 14, wherein the lunette can be brought to the position of the X-axes of the grinding wheel by means of a control device. 16. The grinding machine according to one of claims 9 to 15, in which, by means of a control device, the X-axis of the grinding wheel adjusted by the computer numerical control system can be additionally adjusted to overlap by the type of overlap by the feed rate of the grinding wheel.

Images